<!DOCTYPE html>
<html lang="zh-cn">
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>纯CSS实现内凹导航栏</title>
    <link
      href="https://at.alicdn.com/t/c/font_179247_uja3277echo.css"
      type="text/css"
      rel="stylesheet"
    />
    <style type="text/css">
      * {
        margin: 0;
        padding: 0;
        box-sizing: border-box;
      }
      body {
        display: flex;
        justify-content: center;
        align-items: center;
        min-height: 100vh;
        background-color: #333333;
      }
      .nav {
        width: 375px;
        height: 70px;
        padding: 0 15px;
        border-radius: 5px;
        background-color: #fff;
        position: relative;
        display: flex;
      }
      .nav dd {
        width: 70px;
        height: 70px;
        position: relative;
        list-style: none;
        cursor: pointer;
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        z-index: 10;
      }
      .nav dd i {
        display: block;
        position: relative;
        height: 70px;
        line-height: 70px;
        text-align: center;
        font-size: 24px;
        transition: all 0.5s;
      }
      .nav dd span {
        position: absolute;
        font-size: 12px;
        letter-spacing: 2px;
        transition: all 0.5s;
        opacity: 0;
        transform: translateY(20px);
      }
      .nav dd.on i {
        transform: translateY(-35px);
        color: #ffffff;
      }
      .nav dd.on span {
        opacity: 1;
        transform: translateY(10px);
      }
      .indicator {
        position: absolute;
        top: -50%;
        width: 70px;
        height: 70px;
        background-color: #ff6a00;
        border-radius: 50%;
        transition: all 0.5s;
        border: 6px solid #333333;
      }

      .indicator::before {
        content: "";
        position: absolute;
        top: 50%;
        left: -23px;
        width: 21px;
        height: 21px;
        border-top-right-radius: 20px;
        box-shadow: 1px -10px 0 0 #333333;
      }
      .indicator::after {
        content: "";
        position: absolute;
        top: 50%;
        right: -23px;
        width: 21px;
        height: 21px;
        border-top-left-radius: 20px;
        box-shadow: -1px -10px 0 0 #333333;
      }
      dd:nth-child(1).on ~ .indicator {
        transform: translateX(calc(70px * 0));
      }
      dd:nth-child(2).on ~ .indicator {
        transform: translateX(calc(70px * 1));
      }
      dd:nth-child(3).on ~ .indicator {
        transform: translateX(calc(70px * 2));
      }
      dd:nth-child(4).on ~ .indicator {
        transform: translateX(calc(70px * 3));
      }
      dd:nth-child(5).on ~ .indicator {
        transform: translateX(calc(70px * 4));
      }
    </style>
  </head>
  <body>
    <dl class="nav">
      <dd class="on"><i class="iconfont icon-shouye1"></i><span>首页</span></dd>
      <dd><i class="iconfont icon-zixun"></i><span>资讯</span></dd>
      <dd><i class="iconfont icon-fabu"></i><span>发布</span></dd>
      <dd><i class="iconfont icon-xiaoxi"></i><span>消息</span></dd>
      <dd><i class="iconfont icon-wode"></i><span>我的</span></dd>
      <dt class="indicator"></dt>
    </dl>
    <script>
      const $dd = document.querySelectorAll(".nav dd");
      $dd.forEach((item, index) => {
        item.addEventListener("click", function () {
          $dd.forEach((_dd, _index) => {
            _dd.classList.remove("on");
            this.classList.add("on");
          });
        });
      });
    </script>
  </body>
</html>
